Two line mechanics troubleshooting a chronic hydraulic leak and unfamiliar with B767-300 aircraft systems; cycle the landing gear handle with hydraulic pressure on using the description/operation (D/O) section of the aircraft maintenance manual (amm) instead of the adjustments/tests procedures. Gear pins were not installed; nose gear collapsed.

The report is for an incident that occurred on company B767-300 aircraft. The aircraft received major damage to the front lower section of fuselage when the nose landing gear (nlg) collapsed. The incident was initiated by a chronic leak of the left hydraulic system. I; mechanic X; along with two other mechanics; Y and Z; were trying to find the source of the hydraulic leak. According to the chronic paperwork attached to the maintenance package of the aircraft that night; we had to service the left hydraulic system and perform visual checks of the rudders and tail section aft rigging bay compartment. Mechanic Y noticed hydraulic fluid leaking from the aft drain mast; so we proceeded to investigate the aft rigging bay. We then noticed hydraulic fluid all along the lower section of the aft tail rigging compartment; forward of the tail skid actuator. We found the flexible hoses connected to the actuator saturated in hydraulic fluid; and also one the b-nut's on the return line was loosen by half a turn. So we (mechanic Y and I) proceeded to tighten the line and clean the [tail skid] actuator for leak checks. Now none of the mechanics; including myself; was familiar with the tail skid system on a B767s. So we all headed back to the line maintenance shack to research the tail skid system. We read through chapter 32 and found the tail skid system in the aircraft maintenance manual (amm) 32-71-00). I found the description and operation (D/O) manual and we (mechanic Y and I) proceeded to read through the manual for a better understanding of the system. After reading the manual; we (mechanic Y and I) found a section (page 8 of 10) that talks about the retraction of the [tail skid] actuator. So we went back out to the aircraft after getting more supplies; and began to perform the retraction procedure for the actuator. I positioned myself in the aft tail section to observe any potential leak while mechanic Y went to the cockpit and the other guy (mechanic Z) positioned [himself] on the scissor lift truck. I observed the actuator; looking for leaks as the strut began to retract. While performing the check; we kept in contact using our cellphones. The actuator moved to the fully retracted position and was seated flush against the fuselage; so we began the extension procedure and the aircraft shook violently. I was jarred from my position and fell on lower structure of the aircraft in the aft tail section. After gathering myself; I evacuated the tail section of the aircraft and proceeded to the front of the aircraft where I noticed the nose gear had collapsed causing structural damage.

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Original NASA ASRS Text

Title: Two Line Mechanics troubleshooting a chronic hydraulic leak and unfamiliar with B767-300 Aircraft Systems; cycle the Landing Gear handle with hydraulic pressure on using the Description/Operation (D/O) section of the Aircraft Maintenance Manual (AMM) instead of the Adjustments/Tests procedures. Gear pins were not installed; nose gear collapsed.

Narrative: The report is for an incident that occurred on company B767-300 aircraft. The aircraft received major damage to the front lower section of fuselage when the Nose Landing Gear (NLG) collapsed. The incident was initiated by a chronic leak of the Left Hydraulic System. I; Mechanic X; along with two other Mechanics; Y and Z; were trying to find the source of the hydraulic leak. According to the chronic paperwork attached to the Maintenance package of the aircraft that night; we had to service the Left Hydraulic System and perform visual checks of the rudders and tail section Aft Rigging Bay Compartment. Mechanic Y noticed hydraulic fluid leaking from the aft drain mast; so we proceeded to investigate the aft rigging bay. We then noticed hydraulic fluid all along the lower section of the aft tail rigging compartment; forward of the Tail Skid Actuator. We found the flexible hoses connected to the actuator saturated in hydraulic fluid; and also one the B-nut's on the Return line was loosen by half a turn. So we (Mechanic Y and I) proceeded to tighten the line and clean the [Tail Skid] actuator for leak checks. Now none of the mechanics; including myself; was familiar with the Tail Skid System on a B767s. So we all headed back to the Line Maintenance shack to research the Tail Skid System. We read through Chapter 32 and found the Tail Skid System in the Aircraft Maintenance Manual (AMM) 32-71-00). I found the Description and Operation (D/O) Manual and we (Mechanic Y and I) proceeded to read through the Manual for a better understanding of the system. After reading the manual; we (Mechanic Y and I) found a section (page 8 of 10) that talks about the retraction of the [Tail Skid] actuator. So we went back out to the aircraft after getting more supplies; and began to perform the retraction procedure for the actuator. I positioned myself in the Aft Tail section to observe any potential leak while Mechanic Y went to the cockpit and the other guy (Mechanic Z) positioned [himself] on the Scissor Lift Truck. I observed the actuator; looking for leaks as the strut began to retract. While performing the check; we kept in contact using our cellphones. The actuator moved to the fully retracted position and was seated flush against the fuselage; so we began the extension procedure and the aircraft shook violently. I was jarred from my position and fell on lower structure of the aircraft in the aft tail section. After gathering myself; I evacuated the tail section of the aircraft and proceeded to the front of the aircraft where I noticed the nose gear had collapsed causing structural damage.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.